super(stopwatch);
  }

  @Override
  final void doSetRate(double permitsPerSecond, long nowMicros) {
    resync(nowMicros);
    double stableIntervalMicros = SECONDS.toMicros(1L) / permitsPerSecond;
    this.stableIntervalMicros = stableIntervalMicros;
    doSetRate(permitsPerSecond, stableIntervalMicros);
  }

  abstract void doSetRate(double permitsPerSecond, double stableIntervalMicros);

  @Override

   */
  public final void setRate(double permitsPerSecond) {
    checkArgument(permitsPerSecond > 0.0, "rate must be positive");
    synchronized (mutex()) {
      doSetRate(permitsPerSecond, stopwatch.readMicros());
    }
  }

  abstract void doSetRate(double permitsPerSecond, long nowMicros);

  /**
   * Returns the stable rate (as {@code permits per seconds}) with which this {@code RateLimiter} is